The demands for medical and particularly dental equipment to be sterile has increased. To permit these instruments to be sterilized in a limited period of time, it is required that they are first cleaned so that germs and spores can not lay protected in contaminations left on the instruments. The efficiency of the cleaning is very much dependent on how long the instrument has been resting between use and cleaning.
An instrument is often sterilized in an impermeable package which prevents the instrument from being contaminated after sterilization. If the instrument is not packaged, it is only considered sterile until the sterilization equipment has been opened. Cleaning can not be effected in the packaged but the instruments have to be packed after the cleaning.
For instruments requiring several steps in the sterilization process it is not possible to have them packed during the entire process. If the instrument shall be both washed before the sterilization and lubricated after the sterilization, this must be solved in another manner.
Another method could be to refrain from picking out the instruments from the process chamber until they are to be used. As sterilizers are large apparatuses positioned in separate rooms and which sterilize several instruments at the same time this will not work out satisfactorily.
EP-A1-0 638 298 discloses a cassette for hygienic treatment of dental instruments in a pressure-proof sealable chamber. The cassette incorporates a number of adapters as holders for the instruments, which adapters are connected to conduits for cleaning and washing the interior of the instruments with the aid of treatment media. The exterior of the instruments is treated with treatment media which is sprayed thereon by nozzle equipped tubes that project into cassette. In the conduits for the treatment media are provided magnetic valves, which open and close by means of a micro processor. The treatment time is about 30 minutes. The design of the apparatus with a cassette and a number of adapters and the length of the treatment time means, that the apparatus has to be used for several patients, which means, that as soon as the cassette has been opened for one patient, the remaining instruments do not longer fulfil the demands for sterility. The rather big sterilizing capacity of the apparatus furthermore means, that it might take some time before the next hygienic treatment can be effected, with the consequence that the instrument have been exposed during different long times and therefore should need different treatment times or that all instruments always are treated during a time of excessive length, in order to avoid that strains of germs have survived.